Nov 3, 2025 3 min read

Image announcing Arne Brasseur speaking about the Gaiwan Stack at the London Clojurians on November 11, 2025

MCP-SDK Released

New blog post! mcp-sdk: an Introduction to creating an MCP service with Clojure. Last month we released mcp-sdk, a pure Clojure SDK for working with MCPs. If you’d like to create your own MCP service, check out our blog post to help you get started.

What’s in a name?

Most of our open source projects carry the Lambda Island name. You find them under lambdaisland on github, and under [com.]lambdaisland on clojars. Lambda Island is the name I chose when in 2017 I decided to get into screencasting, making premium video tutorials about Clojure. These videos are still online, nowadays you can watch them all for free.

The first library I released under the same name was lambdaisland/uri, a small utility I extracted from the code base that runs the lambdaisland website. Many more libraries and tools would follow. Kaocha (2018), Ornament (2021), Launchpad (2021), Plenish (2022), CLI (2024), just to name a few highlights.

Since 2019 the maintainance and stewardship of what are by now literally dozens of projects falls upon Gaiwan colleagues and me. This is a collection of open source that Gaiwan proudly shares for the betterment of the Clojure community, but the old name has stuck. I’ve never been quite sure what to do with that. People would tell me I should rename Gaiwan to Lambda Island to benefit from the name recognition, or go the other way, and migrate all these projects over to the Gaiwan team and organisation. I will agree this confusion of names has not done us any favors.

For me there’s always been a clear distinction though. Lambda Island is not an official entity, but if it was, it would be a non-profit. It’s our connection to the community, hence why Lambda Island has an opencollective page, or why we run the ClojureVerse forum. There’s no commercial motive here, rather it’s in our DNA to give back, to share, and to strengthen the community and ecosystem we benefit from. I guess it’s my own anti-corporate tendencies that have always wanted to keep that separate from the business, even though Gaiwan is about as indy as it gets. A handful of people running a bootstrapped business.

Lately however we have at last started releasing newer stuff directly under the Gaiwan name, notably our in-progress IAM implementation called Oak. This is a project that distills years of consulting experience, and so it felt right to put our own name on it. A mark of the maker. Oak is also a starting point for us to explore commercial possibilities in the identity space. If that sounds like something you’d like to chat to us about, get in touch!

Reset password screenshot from Oak, our IAM implementation

Coming Up

Arne will do an online talk about The Gaiwan Stack on November 11, 18:30 London / 19:30 CET. Gaiwan has built a lot of Clojure applications over the years, and we’ve developed an opinionated stack and tooling. It’s overdue that we share more of these learnings.

What We Are Reading

• Europe’s plan to ditch US tech giants is built on open source - and it’s gaining steam ’ Digital Sovereignity is a hot topic in Europe, and it’s something we’ve been having a lot of conversations about inside the Gaiwan team as well. We’ve started the process of migrating from Github to our own Forgejo instance. It’s a space we are actively exploring to see if we can help European tech companies break their dependency on US clouds.
• The Majority AI View Some of you may have read the post from our founder back in September where he explains his view on AI and some of the cognitive dissonance it causes (link). While we do keep an eye on these technologies and try to evaluate their worth, like the people in this article we are concerned and sceptical as well.* *
• Your data model is your destiny: “when code is cheap, competition is fierce, and vertical depth matters, your data model is the foundation of your moat. The companies that win won’t be those with the most or even the best features. AI will democratize those. The winners will be built on a data model that captures something true about their market, which in turn creates compounding advantages competitors can’t replicate.”